June 13 Fledge Watch continues

There are several ways used to determine the age of a red tail hawk chick. Using the Cornell method both J1 and J2 were born in the same 24 hour period; they are both 49 days old today and Little J3 is 45 days old. The average age that a chick has fledged in the last three years is 46.1 days. Of the Js, only one has fledged, J2 who fledged yesterday at age 48 days. As you might then imagine, Cornell RTH watchers were on pins and needles today expecting J1 and J3 to both fledge at the same time. They are buddies – Big Sis taking care of Little Brother.

J1 allopreening J3. Preening is when a bird cleans their own feathers. Allopreening is when a bird preens another bird. Some hawkaholics call it kissing. Arthur is often seen allopreening Big Red when they are resting.
Arthur allopreening Big Red on the Bradfield Building ledge.

So what happened today? J2, having spent the night sleeping in a pine tree across the road, returns to the nest for breakfast.

J2 has really mastered hovering, flying, and landing on rails and branches. Here he is sitting on the rail before jumping down to join J1 and J3 for a chippy breakfast.
This is Arthur bring prey to the nest. Note how high the nest is on the grating. You can see one of the chicks clearly in the nest bowl looking at their dad bring food.
Arthur delivering a squirrel to the nest in early April. Notice the pine needles. These are thought to keep insects from the nest.

Parents will continue to provide most of the food for the chicks until they are fully able to hun themselves. Even then it is not unusual for chicks to chase their parents begging for food.

Ever though about what a young nestling might eat? Ah, probably not! Unless you are a hawkaholic and joke about making chocolate chippie cupcakes with a squirrel glaze? All kidding aside, food is essential to the well being of these red tail hawks.

Prey is delivered to the nest beginning at just before sunrise and just after sunset. On average, in this prey rich area, food items are delivered ten to fifteen times a day. This provides each nestling with an average of 410-730 grams of food per day. The Cornell Labs keep a daily log of which parent delivers prey and when and what it was. There have been more than 300 deliveries so far since the chicks hatched in late April. The male – in this case Arthur – is the main hunter. He has brought in a snake, cottontail bunnies, goslings, pigeons, mature grey squirrels (didn’t like them so much because they have tough skins), smaller squirrels, voles, Starlings, other small birds, and a whole lot of chipmunks. In fact, chipmunks comprise approximately 77% of the chick’s diet this year according to the prey log. In 1990 a study was done and at that time, the red tail hawk diet consisted of 68% mammals, 17.5% other birds, 7% reptiles and amphibians, and 3.2% invertebrates. The list of possible prey items (food) depends on the geographical location of the nest and the amount of prey available. Hawks have 20/2 vision which means that they can see something at 20 feet as if it were only 2 feet away. This is a tremendous help in hunting for food as you can well imagine. The survival of the red tail hawks depends on their prey base.

Big Red and Arthur have a territory of 1.5-2 square miles. The area that Big Red and Arthur have on the Cornell campus is abundant with prey. When the chicks were little the chat group used to joke that only people who love hawks talk about and try to identify dead animals. This year we decided that Arthur belonged to “Over Providers Anonymous.” There was so much food that at one time chippies and squirrels almost completely carpeted the nest area.

The three Js in their fur lined nest in early April. J2 is in the front. J3 (back right) leans on his buddy, J1.

Chicks need a lot of food to aid in their tremendous growth. From the time they hatch to an average of six weeks remember, they go from being a bobble headed newborn growing almost as large as their parents. In fact, their wing and tail feathers are longer than their parents to aid in their flight training. During their first molt, these feathers will return to a normal size. They also need a lot of calories to grow so fast.

The three Js being fed by their mother, Big Red. Big Red is the one on the far side at the left. Notice how large the chicks are. They do not have their distinctive red tail feathers yet. These will come in their second year. The two oldest chicks are 41 days old in this picture.

So tomorrow is June 14. To encourage J1 and J3 to fledge, Big Red resorted to bringing thorn branches to the nest around 7pm! Stay tuned.

I am grateful to Barb Michel Matthews, Karel Sedlasek, and the Cornell Lab for the images in this blog.

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